Validating Genesys Cloud EventBridge Interaction Schemas with TypeScript Zod and DLQ Routing

What You Will Build

• A TypeScript AWS Lambda handler that receives Genesys Cloud EventBridge interaction events, validates them against a JSON Schema draft using Zod, and discards malformed payloads.
• The validation pipeline routes failed events to an AWS SQS dead-letter queue with structured error diagnostics.
• The implementation covers TypeScript, Node.js 18+, AWS SDK v3, and the Zod runtime validator.

Prerequisites

• AWS IAM role with sqs:SendMessage and logs:CreateLogGroup permissions
• Genesys Cloud EventBridge integration configured to publish Conversation or Interaction events
• Node.js 18+ runtime with TypeScript 5+ compiler
• External dependencies: npm install zod @aws-sdk/client-sqs @types/aws-lambda axios

Authentication Setup

Genesys Cloud EventBridge events are pushed via AWS IAM event rules and do not require OAuth for ingestion. However, if your validation pipeline must verify interaction legitimacy against the Genesys Cloud platform, you must authenticate using OAuth 2.0 client credentials. The following TypeScript utility fetches and caches an access token.

import axios from "axios";

const GENESYS_ORGANIZATION_ID = process.env.GENESYS_ORGANIZATION_ID || "your-org-id";
const GENESYS_CLIENT_ID = process.env.GENESYS_CLIENT_ID || "";
const GENESYS_CLIENT_SECRET = process.env.GENESYS_CLIENT_SECRET || "";

const BASE_URL = `https://${GENESYS_ORGANIZATION_ID}.mypurecloud.com`;
let cachedToken: string | null = null;
let tokenExpiry: number = 0;

export async function getGenesysAccessToken(): Promise<string> {
  const now = Date.now();
  if (cachedToken && now < tokenExpiry) {
    return cachedToken;
  }

  const response = await axios.post(
    `${BASE_URL}/api/v2/oauth/token`,
    {
      grant_type: "client_credentials",
      client_id: GENESYS_CLIENT_ID,
      client_secret: GENESYS_CLIENT_SECRET,
      scope: "conversation:read analytics:query"
    },
    {
      headers: { "Content-Type": "application/x-www-form-urlencoded" }
    }
  );

  cachedToken = response.data.access_token;
  tokenExpiry = now + (response.data.expires_in * 1000) - 60000; // Refresh 1 minute early
  return cachedToken;
}

The endpoint /api/v2/oauth/token requires the conversation:read and analytics:query scopes. The token is cached in memory with a one-minute safety buffer to prevent edge-case expiration during high-throughput Lambda invocations.

Implementation

Step 1: Define the Zod Schema for EventBridge Interaction Payloads

Genesys Cloud EventBridge events wrap the actual interaction data inside a detail object. The JSON Schema draft 2020-12 specification for conversation events defines strict types for timestamps, arrays of participants, and nested metadata. Zod provides runtime validation that mirrors this draft.

import { z } from "zod";

// Mirrors Genesys Cloud EventBridge JSON Schema Draft 2020-12 for Conversation Events
export const GenesysEventBridgeSchema = z.object({
  id: z.string().uuid(),
  source: z.literal("genesyscloud"),
  account: z.string(),
  time: z.string().datetime(),
  region: z.string(),
  detailType: z.string(),
  detail: z.object({
    conversationId: z.string().uuid(),
    type: z.enum(["voice", "chat", "email", "social", "sms", "callback"]),
    initiatedTimestamp: z.string().datetime(),
    participants: z.array(
      z.object({
        id: z.string().uuid(),
        name: z.string().nullable(),
        type: z.enum(["user", "external", "system"]),
        roles: z.array(z.string()),
        state: z.string()
      })
    ),
    metadata: z.record(z.string(), z.unknown()).optional()
  })
});

export type GenesysEventBridgePayload = z.infer<typeof GenesysEventBridgeSchema>;

The schema enforces UUID formats, strict enum values for type and roles, and nullable strings for optional participant names. Any deviation from this structure triggers a Zod ZodError.

Step 2: Build the Validation Engine with Zod and Error Routing

The validation engine consumes raw EventBridge records, runs them through Zod, and routes failures to an SQS dead-letter queue. The DLQ payload includes the original event, validation errors, and a timestamp for downstream debugging.

import { SQSClient, SendMessageCommand } from "@aws-sdk/client-sqs";

const sqsClient = new SQSClient({ region: process.env.AWS_REGION || "us-east-1" });
const DLQ_URL = process.env.DLQ_URL || "";

interface ValidationErrorPayload {
  originalEvent: unknown;
  validationErrors: string[];
  timestamp: string;
}

export async function routeToDLQ(event: unknown, errors: string[]): Promise<void> {
  const payload: ValidationErrorPayload = {
    originalEvent: event,
    validationErrors: errors,
    timestamp: new Date().toISOString()
  };

  const command = new SendMessageCommand({
    QueueUrl: DLQ_URL,
    MessageBody: JSON.stringify(payload)
  });

  await sqsClient.send(command);
}

export function validateEventBridgePayload(rawEvent: unknown): { success: boolean; data?: GenesysEventBridgePayload; errors?: string[] } {
  const result = GenesysEventBridgeSchema.safeParse(rawEvent);
  
  if (!result.success) {
    const errors = result.error.issues.map(issue => {
      const path = issue.path.join(".");
      return `Path: ${path || "root"} | Code: ${issue.code} | Message: ${issue.message}`;
    });
    return { success: false, errors };
  }

  return { success: true, data: result.data };
}

The safeParse method returns a structured error array instead of throwing. Each error includes the JSON path, Zod error code, and human-readable message. The DLQ routing uses AWS SDK v3 commands for non-blocking asynchronous dispatch.

Step 3: Integrate Genesys Cloud API Verification and DLQ Dispatch

Validating the schema ensures structural correctness, but it does not guarantee the interaction exists in Genesys Cloud. The following step verifies the conversationId against the Genesys Cloud API, implements pagination handling, and includes 429 retry logic.

import axios from "axios";

async function verifyConversationExists(conversationId: string, token: string): Promise<boolean> {
  const maxRetries = 3;
  let attempt = 0;
  let hasNextPage = true;
  let pageNumber = 1;
  const pageSize = 100;

  while (hasNextPage && attempt < maxRetries) {
    try {
      // OAuth scope required: conversation:read
      const response = await axios.get(`${BASE_URL}/api/v2/conversations`, {
        headers: { Authorization: `Bearer ${token}` },
        params: {
          pageSize,
          pageNumber,
          type: "voice", // Filter to reduce response size
          sortOrder: "desc",
          sortColumn: "initiatedTimestamp"
        }
      });

      const conversations = response.data.entities || [];
      const exists = conversations.some((c: any) => c.id === conversationId);
      
      if (exists) return true;

      // Pagination handling
      if (response.data.pageCount && pageNumber < response.data.pageCount) {
        pageNumber++;
        hasNextPage = true;
      } else {
        hasNextPage = false;
      }
    } catch (error: any) {
      const status = error.response?.status;
      
      if (status === 429 && attempt < maxRetries - 1) {
        const retryAfter = error.response?.headers["retry-after"] ? parseInt(error.response.headers["retry-after"]) * 1000 : Math.pow(2, attempt) * 1000;
        await new Promise(resolve => setTimeout(resolve, retryAfter));
        attempt++;
        continue;
      }

      if (status === 401 || status === 403) {
        throw new Error(`Authentication failed with status ${status}. Verify OAuth scopes: conversation:read`);
      }

      if (status && status >= 500) {
        throw new Error(`Genesys Cloud server error: ${status}. Retries exhausted.`);
      }

      throw error;
    }
  }

  return false;
}

The endpoint /api/v2/conversations supports pageSize and pageNumber parameters. The loop continues until the target conversation is found or pagination completes. The 429 retry logic respects the Retry-After header when present, otherwise falling back to exponential backoff. Authentication errors (401, 403) fail immediately to prevent wasted cycles.

Complete Working Example

The following module combines schema validation, API verification, and DLQ routing into a production-ready AWS Lambda handler. Copy the code, set the environment variables, and deploy to a Lambda function with the SQS DLQ ARN attached.

import { APIGatewayProxyEvent, Context } from "aws-lambda";
import { validateEventBridgePayload, routeToDLQ } from "./validator";
import { getGenesysAccessToken } from "./auth";
import { verifyConversationExists } from "./api-verify";

export const handler = async (event: APIGatewayProxyEvent, context: Context): Promise<any> => {
  const records = JSON.parse(event.body || "[]") as unknown[];
  const processedResults: any[] = [];

  for (const rawRecord of records) {
    const validation = validateEventBridgePayload(rawRecord);

    if (!validation.success) {
      await routeToDLQ(rawRecord, validation.errors || []);
      processedResults.push({ status: "rejected", reason: "schema_validation_failed" });
      continue;
    }

    const payload = validation.data;
    context.callbackWaitsForEmptyEventLoop = false;

    try {
      const token = await getGenesysAccessToken();
      const exists = await verifyConversationExists(payload.detail.conversationId, token);

      if (!exists) {
        await routeToDLQ(rawRecord, ["Conversation ID not found in Genesys Cloud platform"]);
        processedResults.push({ status: "rejected", reason: "conversation_not_found" });
        continue;
      }

      processedResults.push({ status: "accepted", conversationId: payload.detail.conversationId });
    } catch (error: any) {
      const errorMessage = error instanceof Error ? error.message : "Unknown verification error";
      await routeToDLQ(rawRecord, [errorMessage]);
      processedResults.push({ status: "rejected", reason: "verification_error" });
    }
  }

  return {
    statusCode: 200,
    headers: { "Content-Type": "application/json" },
    body: JSON.stringify({ processed: processedResults.length, results: processedResults })
  };
};

The handler processes batched EventBridge records, validates each against the Zod schema, verifies existence via the Genesys Cloud API, and routes failures to the DLQ. The callbackWaitsForEmptyEventLoop flag is disabled to prevent Lambda from waiting for SQS promises to resolve, improving cold-start performance.

Common Errors & Debugging

Error: 401 Unauthorized on /api/v2/conversations

• Cause: The OAuth token is expired, missing, or the client credentials lack the required scopes.
• Fix: Verify GENESYS_CLIENT_ID and GENESYS_CLIENT_SECRET match a Genesys Cloud OAuth application. Ensure the application has conversation:read assigned.
• Code showing the fix:

// Add explicit scope validation during token fetch
if (!response.data.scope?.includes("conversation:read")) {
  throw new Error("OAuth application missing conversation:read scope");
}

Error: 429 Too Many Requests on Genesys Cloud API

• Cause: The validation pipeline exceeds Genesys Cloud rate limits (typically 100 requests per second per tenant for conversation endpoints).
• Fix: Implement request throttling at the Lambda concurrency level or increase the retry delay. The provided verifyConversationExists function already handles 429 with exponential backoff.
• Code showing the fix:

// Increase backoff multiplier for sustained 429s
const retryAfter = Math.max(1000, Math.pow(2, attempt) * 1000) + (Math.random() * 500);
await new Promise(resolve => setTimeout(resolve, retryAfter));

Error: Zod ValidationError on detail.initiatedTimestamp

• Cause: Genesys Cloud EventBridge payloads occasionally contain malformed ISO 8601 strings or missing timezone offsets during platform migrations.
• Fix: Adjust the Zod schema to accept flexible datetime formats or normalize timestamps before validation.
• Code showing the fix:

// Use z.coerce.date() instead of z.string().datetime() for flexible parsing
initiatedTimestamp: z.coerce.date(),

Official References

• Genesys Cloud EventBridge Integration Documentation
• Zod Runtime Validation Reference
• AWS SDK v3 SQS Client Documentation